Add 3.13 in pyproject.toml

Author: schloerke

pyproject.toml

@@ -19,6 +19,7 @@ classifiers = [
   "Programming Language :: Python :: 3.10",
   "Programming Language :: Python :: 3.11",
   "Programming Language :: Python :: 3.12",
+  "Programming Language :: Python :: 3.13",
   "Programming Language :: Python :: Implementation :: PyPy",
   "Topic :: Internet :: WWW/HTTP :: Dynamic Content",
   "Topic :: Software Development :: Libraries :: Python Modules",